In newborn children, the nerves and brain function that control eye movement and image processing begin to converge during the first 9 months after birth. Sometimes this natural process can go wrong and their eyes can start to cross inward (esotropia) or separate outwards (exotropia). This can prevent the brain from receiving simultaneous overlapping images from each eye to provide a true 3D depth realization. Surgery is sometimes needed to bring the eyes back into reasonable alignment but the brain still may suppress one eye or the other. In other situations, though the eyes are aligned, one eye can become dominant and the other “lazy” (amblyopia). Again the brain needs to learn how to process the images from both eyes simultaneously and equally. The nerves that control the eye muscles and receive the input of each eye need to be trained such as for binocular or stereo vision.
In small children with vision problems, the best results happen if therapy is started before the age of six when the wiring becomes mostly permanent. The older the child gets, the harder it is to correct the defects. So their defective eyesight should be corrected as early as possible. However, there are challenges in working with very young children. For example, they have more difficulty comprehending the need for the therapy; and they may not be able to execute instructions for vision therapy, particularly when the tasks are boring to them. The challenge is further exacerbated when the training session requires performing certain tasks repetitively for a long duration of time.
Instead of performing vision therapy, some parents opt for corrective eye surgery. For example, surgery could bring crossed eye back into near alignment. However, even after the surgery, their brain still prefers to use one eye over another. They need to be trained or to be retrained to see with both eyes.
Such eye defects are not limited to small children. Adults may need vision therapy also. For example, according to one study, two or more percent of the population in the United States do not have stereo vision.
Prior methods of treating amblyopia include patching. Patching is an effective therapy for amblyopia when patients are compliant. However compliance, particularly in older children, could be difficult primarily due to the debilitating effects of decreased vision while wearing a patch, along with social, cosmetic, and comfort issues that could make consistent therapy progressively more difficult with increasing age.
It is desirable to have methods, systems and apparatuses for providing vision therapy to address the eye ailments described above.